Comparative Life Cycle Assessment of Safety Shoes Toe Caps Manufacturing Processes

Toe caps are fundamental components of safety footwear used to prevent injuries which can be caused by falling objects. They can be realized by exploiting different materials (metal, composites and plastics) and manufacturing processes (stamping, injection molding, compression molding, etc.). However, they have always to fulfill the stringent requirements of safety regulations. In addition, in order to guarantee an ergonomic use, they must be as light as possible. It is estimated that at least 300 million pairs of safety footwear, with 600 million of toe caps, end up in landfill or are incinerated every year. This huge amount of wastes generates a relevant environmental impact, mainly attributable to toe caps manufacturing. In this context, it is important to develop new solutions which minimize the environmental impacts of toe caps manufacturing. Among others, the reuse of carbon fiber prepreg scraps has been recognized as a valid method to produce effective toe caps. In this paper, a detailed analysis of the environmental impacts associated to toe caps realized with reclaimed prepreg scraps has been conducted exploiting the Life Cycle Assessment methodology. The results have been compared to those obtained by analyzing toe caps realized in steel, aluminum, polycarbonate and glass fiber composite. Results demonstrate that the reclaim process for carbon fiber prepreg scraps can be a valid circular economy model to produce more sustainable toe caps for safety footwear.

Vibration response of glass fiber composite multi-layer graded corrugated sandwich panels

Based on the criteria of equal total height and relative density, a series of glass fiber composite multi-layer graded corrugated sandwich panels (MLGCSPs) with different configurations is designed and fabricated by an in-house hot-molding secondary molding method. The effects of arrangement modes, graded corrugated cores and corrugated topologies on the vibration behavior of the present MLGCSPs are comprehensively investigated by the vibration shaker tests. The results reveal that the arrangement modes, graded arrangement and topologies of the corrugated cores all have significant influences on the frequency responses, and vibration reduction of the present MLGCSPs. The arrangement mode II and III generally have significantly higher resonant frequencies and vibration attenuation performance in the low frequency range, but the arrangement mode I shows better vibration reduction and isolation performance in the higher frequency range. It is possible to simultaneously achieve higher fundamental frequency and lower amplitude of the structures by optimizing the arrangement mode and gradient configuration. Subsequently, finite element simulation is carried out to systematically analyze the vibration responses of the composite MLGCSPs with different configurations. The consistency between numerical and experimental results is quite well. Finally, the effects of structural parameters on the vibration characteristics of the present structures are also revealed. Some conclusions are obtained, which can provide some meaningful guidelines for the vibration reduction design of such type of multi-layer structures.

Experimental analysis of composite materials leaf spring used in automotive

product modifications or replacement of old products with new and improved material items. Vehicle suspension systems are another area where these developments are carried out on a regular basis. More efforts are being made to improve the user's comfort. Appropriate combination of comfort riding attributes and economics in leaf spring production becomes an evident requirement. Many changes have been made to the suspension system throughout time in order to enhance it. Some of the most recent suspension system innovations include the invention of the parabolic leaf spring and the usage of composite materials for these springs. The implementation of composite materials by replacing steel in conventional leaf springs of a suspension system. Composite material having a lot of good properties like simple fabrication, low weight and low cost to performance .The purpose of this study is to investigate the structural properties of a hybrid leaf spring consisting of 95% Epoxy, 5% carbon, 5% glass fiber, and 5% hybrid carbon-glass fiber composite. The various specimens were produced using the manual layup method, specimen were subjected to tensile, hardness, and fatigue tests, with all data reported and compared. The experimental results showed an increase in Hardness, Tensile, and fatigue life when the reinforcing fibers are applied. The best results of the mechanical test obtained when hybrid reinforcement was applied.

Cyclic Relaxation, Impact Properties and Fracture Toughness of Carbon and Glass Fiber Reinforced Composite Laminates

In this paper, the mechanical properties of fiber-reinforced epoxy laminates are experimentally tested. The relaxation behavior of carbon and glass fiber composite laminates is investigated at room temperature. In addition, the impact strength under drop-weight loading is measured. The hand lay-up technique is used to fabricate composite laminates with woven 8-ply carbon and glass fiber reinforced epoxy. Tensile tests, cyclic relaxation tests and drop weight impacts are carried out on the carbon and glass fiber-reinforced epoxy laminates. The surface release energy GIC and the related fracture toughness KIC are important characteristic properties and are therefore measured experimentally using a standard test on centre-cracked specimens. The results show that carbon fiber-reinforced epoxy laminates with high tensile strength give high cyclic relaxation performance, better than the specimens with glass fiber composite laminates. This is due to the higher strength and stiffness of carbon fiber-reinforced epoxy with 600 MPa compared to glass fiber-reinforced epoxy with 200 MPa. While glass fibers show better impact behavior than carbon fibers at impact energies between 1.9 and 2.7 J, this is due to the large amount of epoxy resin in the case of glass fiber composite laminates, while the impact behavior is different at impact energies between 2.7 and 3.4 J. The fracture toughness KIC is measured to be 192 and 31 MPa √m and the surface energy GIC is measured to be 540.6 and 31.1 kJ/m2 for carbon and glass fiber-reinforced epoxy laminates, respectively.

Vibrational Analysis on Hemp and Okra Fibres Mixed Glass Fiber Polyester Composite

In transverse vibrations the element moves to and fro in a direction perpendicular to the direction of the advance of the wave. To determine the vibration characteristics i.e., natural frequencies and mode shapes, modal analysis is a process for a structure or a machine component while is being designed. In real life, aero planes, missiles, rockets, space vehicles, satellites, sub marines etc are modeled as free-free mechanical systems. In this paper an attempt was made to compare natural frequency for two composite materials- ladies finger with Glass fiber composite and Hemp with Glass fiber composite by taking as cantilever beams. The cantilever beam which is fixed at one end is vibrated to obtain the natural frequency, mode shapes at four different modes. A simple low cost demonstration experiment is performed in this paper by using common apparatus in order to compare theoretical, numerical (FEM analysis) profiles of two free-free thin two rectangular composite beams of dimensions 305*49.5* 7 in mm. Keywords: Natural frequencies, Mode shapes, Vibration characteristics, Ladies finger fiber, Hemp fiber, Glass fiber, FEM analysis, Free-Free system.

Interfacial, mechanical, and thermal behavior of PEI/glass fiber welded joints influenced by hygrothermal conditioning

This work aims to characterize the influence of hygrothermal conditioning on the mechanical and thermal behavior as well as the fractographic aspects of the interface of poly(ether imide) and glass fiber composite joints welded by electrical resistance using 400 mesh of AISI 304 stainless steel. The composites were mechanically characterized by Lap Shear Strength (LSS) and End Notched Flexure (ENF) testing to investigate maximum shear stress and energy from mode II interlaminar fracture toughness. Fractography was performed by SEM, while the influence on glass transition temperature and working temperature were evaluated by Dynamic-Mechanical Analysis and thermogravimetry. In the conditioned samples, the mechanical properties reduced 23% in the LSS test and 28% in the ENF test, while the fractography studies revealed elements of interlaminar and intralaminar fracture in both conditions. Thermal properties did not change significantly to disqualify this composite when applied to welding.

WOOD-GLASS-FIBER COMPOSITE MATERIALS BASED ON POLYESTER RESINS FOR TIMBER RAILWAY SLEEPER STRUCTURES

Wood-glass-fiber composite materials (WGFCM) are used in transport construction (sleepers, switch bars, etc.). Polymer solutions based on furfuralacetone monomer (FAM) served as a matrix for the manufacture of WGFCM. The article suggests using Holex HAS- 2061 polyester resin as a matrix, which, in turn, has chemical resistance, dielectric properties, increased impact strength, having sufficient strength characteristics, and significant extensibility. For the application of the above material in the structural elements of sleepers of logging railways, it is necessary to know its operation under repeated loading. Endurance experiments were conducted at different coefficients of the load application cycle asymmetry pb=0,1; 0,3; 0,6. As a result of the experiments, the values of the endurance limit of the material under study were obtained, which allow us to conclude that it can be used in the construction of timber railway sleepers.

Numerical and Experimental Evaluation of Mechanical and Ring Stiffness Properties of Preconditioning Underground Glass Fiber Composite Pipes

The mechanical and ring stiffness of glass fiber pipes are the most determining factors for their ability to perform their function, especially in a work environment with difficult and harmful conditions. Usually, these pipes serve in rough underground environments of desert and petroleum fields; therefore, they are subjected to multi-type deterioration and damage agents. In polymers and composite materials, corrosion is identified as the degradation in their properties. In this study, tension and compression tests were carried out before and after preconditioning in a corrosive agent for 60 full days to reveal corrosion influences. Moreover, the fracture toughness is measured using a standard single edge notch bending. Ring stiffness of such pipes which, are considered characteristic properties, is numerically evaluated using the extended finite element method before and after preconditioning. The results reported that both tensile and compressive strengths degraded nearly more than 20%. Besides the fracture toughness decrease, the stiffness ring strength is reduced, and the finite element results are in good agreement with the experimental findings.